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Biomedical subjects

C Morgan

Publications and source records attributed to C Morgan.

At least 199 records · Page 11Linked to original sources
PubMed1983

Vasoactive intestinal polypeptide in visceral afferent pathways to the sacral spinal cord of the cat.

Immunohistochemical studies revealed that vasoactive intestinal polypeptide (VIP) is localized primarily to sacral segments of the cat's spinal cord. VIP is most prominent in afferent axons and terminals in Lissauer's tract and in lateral laminae I and V of the dorsal horn. The distribution of VIP terminals is very similar to that of visceral afferent projections identified by horseradish peroxidase. Dye-tracing experiments combined with immunohistochemistry demonstrated that VIP is located in visceral afferent perikarya in the sacral dorsal root ganglia and also in terminals in the sacral autonomic nucleus. These observations suggest that VIP is a neurotransmitter in afferent projections from the pelvic viscera.

Afferent Pathways↗
PubMed1983

Iodine-123 phenylpentadecanoic acid: detection of acute myocardial infarction and injury in dogs using an iodinated fatty acid and single-photon emission tomography.

The ability of an iodinated fatty acid, iodine-123 phenylpentadecanoic acid (1-123 PPA), and single-photon emission computed tomography (SPECT) to detect myocardium injured by temporary or permanent coronary arterial occlusion was evaluated. In 5 control dogs, 11 dogs that underwent 90 to 120 minutes of fixed left anterior descending coronary artery (LAD) occlusion, and 8 dogs that underwent 90 minutes of temporary LAD occlusion and up to 90 minutes of reflow, 2 to 6 mCi of I-123 PPA were injected and the dogs were imaged with SPECT. Control dogs showed relatively uniform uptake and clearance of I-123 PPA in similar left ventricular (LV) regions. Dogs with permanent LAD occlusion were identified by computer algorithm as having regions of decreased I-123 PPA uptake in the infarct-related area and a reduced rate of I-123 PPA clearance (-9.4% in infarct sectors [washin], +3.7% in sectors adjacent to the area of infarction, and +15.4% in control LV sectors [p less than 0.01]). Dogs with temporary LAD occlusion and reperfusion had decreased clearance of I-123 PPA from the regions with infarction; I-123 PPA clearance was -5.2 +/- 16.4% in infarct sectors, 12.7 +/- 7.4% in periinfarct zones, and 30.4 +/- 12% in control LV regions. These data demonstrate that tomographic analysis of I-123 PPA uptake and clearance permits the relatively noninvasive detection of LV myocardium injured by permanent or temporary LAD occlusion and reperfusion.

Animals↗
PubMed1982

An analysis of the importance of the "labile" fraction of glycosylated hemoglobin as determined by a minicolumn method.

The authors have studied the contribution of the labile fraction of glycosylated hemoglobin to the total glycosylated hemoglobin (GH) in hospitalized, poorly controlled diabetic patients, and in a large group of outpatient diabetics using a conventional minicolumn method. A 5-hour saline incubation of erythrocytes or extensive dialysis of hemoglobin against a glucose-free buffer were used to remove the labile glycohemoglobin fraction. Equivalent results were obtained with either method. The change in GH after dialysis in a group of poorly controlled diabetics averaged 1.1%, but only 0.2% in a group of outpatients whose glycohemoglobin levels were being determined on a routine basis. In both groups, the size of the dialyzable fraction increased in proportion to the total GH level, and outpatients with a dialyzable fraction greater than or equal to 2.0% always had GH levels greater than or equal to 12.0%. In most cases where the total glycohemoglobin was less than 12%, the size of the dialyzable fraction approached the limits of the analytical variability of the minicolumn method (SD = approximately 0.3). The authors conclude that while saline incubation of erythrocytes is a practical procedure for removal of labile glycohemoglobin in a routine clinical laboratory, the use of this procedure is probably only necessary for patients with a high level of total glycosylated hemoglobin.

Diabetes Mellitus↗
PubMed1982

The new literacy.

Only with a knowledge of computers can we participate effectively in all facets of modern life. Computer literacy will enable us to keep control over our own professional activities, to contribute effectively to debate, to use the new information systems and to develop our own projects. Anaesthetists can develop this literacy by consistent reading, by doing courses, and by using computers. This paper deals with what we can learn about computer language, and methods of developing a computer project.

Anesthesiology↗
PubMed1981

The distribution of visceral primary afferents from the pelvic nerve to Lissauer's tract and the spinal gray matter and its relationship to the sacral parasympathetic nucleus.

The central distribution of visceral primary afferent fibers from the pelvic nerve of the cast and the relationship of these fibers to preganglionic neurons of the sacral parasympathetic neurons (SPN) have been studied. Horseradish peroxidase (HRP) applied to the cut pelvic nerve was detected ipsilaterally in preganglionic neurons and dorsal root ganglion cells (segments S1-S3), and in central afferent projections to Lissauer's tract (LT), the dorsal columns, the dorsolateral funiculus, and spinal gray matter. The afferent projections were strongest in the region of the SPN (S1-S3) but extended far beyond its limits (e.g., LT was labeled from L4 to Cx7). In the transverse plane, collateral fiber bundles formed a thin shell around the dorsal horn predominantly within lamina I and expanded into terminal fields in the gray matter. The more prominent lateral collateral projection (LCP) extended into laminae V and VI, whereas the medial one (MCP) ended in the dorsal commissure. In longitudinal planes these projections exhibited a periodicity with an interval of approximately 200 micrometer. The distribution of afferent collateral projections overlaps the regions where many preganglionic neurons and their dendritic extensions are located, and also areas known to contain interneurons involved in visceral pathways. A differential distribution of afferents within the SPN was noted where a higher intensity was observed in proximity to those neurons located in laminae V and VI, which innervate the colon, and a lower intensity near neurons located in Lamina VII which innervate the bladder. This is consistent with the known spinal control of colon reflexes and the supraspinal control of bladder reflexes. The widespread rostrocaudal extent of the pelvic primary afferent projection is consistent with the necessity for the integration of somatic and autonomic elements from various levels of the lumbo-sacral-coccygeal spinal cord in the performance of pelvic visceral functions.

Afferent Pathways↗
PubMed1981

Organization of the sacral parasympathetic reflex pathways to the urinary bladder and large intestine.

Electrophysiological and horseradish peroxidase (HRP) techniques have provided new insights into the organization of the sacral parasympathetic reflex pathways to the large intestine and urinary bladder. The innervation of the two organs arises from separate groups of sacral preganglionic cells: (1) a dorsal band of cells in laminae V and VI providing an input to the intestine; and (2) a lateral band of cells in lamina VII providing an input to the bladder. These two groups of cells were separated by an interband region containing tract cells and interneurons. Neurons in the interband region received a visceral afferent input and exhibited firing correlated with the activity of intestine and urinary bladder. It seems reasonable therefore to consider the interband region as a third component of the sacral parasympathetic nucleus. Anterograde transport of HRP revealed that visceral afferents from the intestine and bladder projected into the parasympathetic nucleus. Most of the projections were collaterals from afferent axons in Lissauer's tract that passed in lamina I laterally and medially around the dorsal horn. These afferent collaterals were located in close proximity to preganglionic perikarya and dendrites in laminae I, V and VI. The proximity of visceral afferents and efferents in the sacral cord probably reflects the existence of polysynaptic rather than monosynaptic connections since electrophysiological studies revealed that both the defecation and micturition reflexes occurred with very long central delays (45-70 msec). The reflex pathways mediating defecation and micturition in cats with an intact neuraxis were markedly different. Defecation was dependent upon a spinal reflex with unmyelinated (C-fiber) peripheral afferent and efferent limbs. On the other hand, micturition was mediated by a spinobulbospinal pathway with myelinated peripheral afferent (A-fiber) and efferent axons (B-fiber). Transection of the spinal cord at T12-L2 blocked the micturition reflex but only transiently depressed the defecation reflex. In chronic spinal cats the micturition reflex recovered 1-2 weeks after spinalization; however, in these animals bladder-to-bladder micturition reflexes were elicited by C-fiber rather than A-fiber afferents. The C-fiber afferent-evoked reflex was weak or undetectable in animals with an intact neuraxis. Transection of the spinal cord also changed the micturition reflex in neonatal kittens (age 5-28 days). In neonates with an intact neuraxis bladder-to-bladder reflexes occurred via a long latency spinobulbospinal pathway (325-430 msec). The long latency is attributable to the slow conduction velocity in immature unmyelinated peripheral and central axons. In chronic spinal kittens (3-7 days after spinalization) the long latency reflex was abolished and a shorter latency (90-150 msec) bladder reflex was unmasked. The emergence of this spinal pathway may reflect axonal sprouting and the formation of new reflex connections within the sacral parasympathetic nucleus.

Afferent Pathways↗
PubMed1980

Location and morphology of parasympathetic preganglionic neurons in the sacral spinal cord of the cat revealed by retrograde axonal transport of horseradish peroxidase.

The distribution and morphology of preganglionic neurons in the sacral parasympathetic nucleus (SPN) of the cat have been studied with the horseradish peroxidase (HRP) tracing technique. HRP applied to the cut pelvic nerve was identified in cells located ipsilaterally, primarily in the intermediate gray matter. They formed a column approximately 10 mm long, usually contained within two, but occasionally three, sacral segments, S2 contained a majority of cells. In transverse sections the SPN had the appearance of an inverted "L". Cells were medium-sized, oval or spindle-shaped, and transversely oriented. They were distributed among two major components and one minor one: (1) dorsal band (34%) located mainly in lamina V beneath the dorsal horn (cells and dendrites horizontally oriented), (2) lateral band (64%) along the lateral edge of the gray matter in laminae VII through V (cells oriented dorsoventrally with dendrites extending within the nucleus and into the dorsolateral funiculus), and (3) a small group (2%) of cells at the rostral end of the SPN in lamina VII in the middle of the ventral horn. These data coupled with the results of other investigations indicate that the SPN has a viscerotopic organization wherein the colon is innervated primarily by cells in the dorsal band and the urinary bladder is innervated primarily by cells in the lateral band.

Animals↗
PubMed1979

The central origin of efferent pathways in the carotid sinus nerve of the cat.

The application of horseradish peroxidase to the central cut end of the carotid sinus nerve of the cat produced retrograde labeling of neurons in the ipsilateral medulla in the region of the nucleus ambiguus at anterior-posterior coordinates -8 to -10.5. These data coupled with previous electrophysiological observations suggest that the nucleus ambiguus may be the origin of an efferent inhibitory pathway to the carotid body.

Animals↗